Internal-combustion engine.



A. S. HUSTED.

INTERNAL COMBUSTLON ENGINE.

MPucmon min APR. 26. :915.

A. SIHUSTED.

IMERNAL CUMBUSTION ENGINE.

APPLocATroN msu Mags. |915.

1 ,270,295. Patented Jun@ 25, 191s.

3 SHEETSvSHEE 2.

33a j* rb l ALLAN S. HUSTED, 0F CHICAGO, ILLINOIS.

INTERNAL-COMBUSTION ENGINE.

Specification of Letters Patent.

Patented June 25, 1918.

Application med April 28. 1915. Serial No. 23,852.

To all whom t may concern:

Be it known that I, ALLAN S. HUSTED, a citizen oi' the United States, residing at Chicago, iu the county of Cook and State of Illinois. have invented a certain new and useful Improvement in lnternal-Con'ibustion Engines, of which the following is a full, clear. concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

Thisl invention relates to improvements in internal combustion engines.

(lne object of the invention is to rovide an internal combustion engine, an more particularly n gasolcne engine for autoincbile use, in which a complete scavenging of the cylinder is obtained during each c cle of operations, the engine operating on t e two cycle principle.

Other objects of the invention are to provide an engine of the character described which is of compact arrangement; which employs an auxiliary or scavenging piston movable on the power stroke with the power piston and independently movable of the latter on the return stroke; which has a scavenging piston havin a longer stroke than that of the power piston; which employs self-contained, self-actuated means for operating the auxiliary or scavenging piston on its return strokes, which means are con fined within the power piston; which is provided with a single member controlling the valves and ports of intake and exhaust; which will run at a lower speed than the ordinary 4 cycle type engine; which is provided with automatically operated means governingthe s eed of the auxiliary' piston;

which is provi ed with intake and exhaust ports of relatively large area; and which consists of relativelyvfew parts, simply arranged.

The invention furthermore consists in the improvements of the parts and devices and in the novel combinations of the parts -and devices, as herein shown, described or claimed.v

ln the drawing forming a part of this specilication, I have illustrated one embodiment of my invention and in said drawings Figure 1 is a vertical central sectional view of an engine employing two power cylinders arranged Ain tandem, the parts being shown in the position when an explosion is about to take place in the upper cylinder. Fig. `2 is a view similar to Fig. 1 but s'howi'ng the parts after the explosion in the upper cylinder has taken place and the power piston has traveled about half of its stroke. Fig. 3 is i a view similar to Figs. 1 and 2 but showing the end of the downward stroke of the piston and 'with the auxiliary piston for the upper cylinder returned to its full height, the auxiliary piston in the lower cylinder bring also lmoved up from its lowermost position, as shown in Fig. 1, and the parts so arranged that an explosion is about to take place in the lower power cylinder. Fig. 4 1s a side elevation of the structure illustrated in Figs. 1, 2 and 3. Figs. 5, 6 and 7 are enlarged transverse sectional views taken substantially on the lines 5--5, M and 7 7, respectively, of Fig. 1, and Fig. 8 is an enlarged detail sectional view to more clearly illustrate the ports and passages of one of the power pistons, its associate auxiliary piston and the head of the cylinder.

Referring to said drawing, the main casting havin two power cylinders formed therein is esignated generally by the reference A, and as shown, has the heads A' A bolted thereto. The castingA is rovided with an upper power cylinder B an( a lower power cyllnder B. Mounted within the power cylinders and reciprocating back and forth therein, in the usual manner, is a double ended power piston designated generally by the reference C, and, as shown, the same comprises a single casting having an upger power piston D and a lower power piston the latter being each provided with a hollow, rigid sleeve 10 which communicates with a central chamber 11, the sleeves 10 each forming air cylinders within-"fwhich reciprocate air pistons E and E', each air piston being connected by a piston rod 12 with its corresponding auxiliary or scavengi ing piston F and F', the auxiliary pistons F and F being interposed between their corresponding power pistonsand the heads of the power cylinders. The double ended piston C is also provided with an integral transversely extending bearing 13 for the piston pin 14g working in slots 1'14 in the casting A and 4to which is connected oppostely disposed pitmen 15--15 (see Fig. 4) the lower ends of said pitmen bein connected to cranks on the power sha not shown, as will be understood. The air cylinders 10` andi chalnber11 are closed, exce t for ports at the outer ends of each of e cylinders 10, as will be explained herein,

' rent 1n the usual manner.

after. ln thc head of each power cylinder is provided a spark plug 16, of any desirable type, and connected to a source of cur- 'l`he ex lesive mixture is admitted through a mani old 1T which communicates with passages 18-18 formed in jacket of the power cy inder and having inlet ports or intakes 19-19 adapted to communicate with the power cylinders B and B. The casting A is also provided with suitable water jacket spaces 2li-20 for cooling purposes in the usual manner. As will be noted, the intake ports for the explw sive. mixture are so located as to be uncovered when each power piston is at the end of its out or power stroke. A plurality of exhaust ports 21--21 are provided for each power cylinder, which exhaust ports are l0V cated closely adjacent the heads of the cylinders, it being nmlerstood that a plurality of such exhaust ports, as well as intake ports, are provided for each cylinder, the same be- A ing arranged ciremnferentially of the cylinders and connnunicating with each other.

interposed between the various pistons and the walls of the power cylinders is a c lindrical sleeve 22 having the ends thereof slidable in suitable recesses 23-23 'in the heads of the cylinders, said sleeve 22 having a limited reciprocating movement, the timing of which is governed by cams on the crank shaft (not shown) through the intermediary of rods 24 which connect with the sleeve and pass through the lower cylinder head (see Figs. 1, 2 and 3). Said sleeve 2L' is provided with an upper and lower seriesl of circularlyt arranged intake ports 25- 25 ada ted to aline, at the `proper time, with the inta e ports 19-19. Near cach of itsI outer ends the sleeve 22 is also provided with a series of circularly arranged exhaust ports 26-26 adapted to be alined, at the 'proper time, with the exhaust orts 21-21 of each power cylinder. In or er to prevent the admission of the explosive mixture helow thc power pistons upon their respective return or in-strokes, eaeh'power'piston D and l) is provided with a s irt 27-27 which covers the ports 25-25 in the Sleeve. i In order to open the spaces between the cylinder 10 and the sleeves 27 to the atmosphere, the sleeves 27 and sleeve 22 are suitably slotted in alinement with the slots 114, that is, directly in back of the cylinder 10 as the latter is viewed in Fig.` 1. Near each end of the sleeve 22 it is provided with a series of circularly arran ed by-passes 28-28, for a purpose hereina ter described. Said sleeve .22 is also providedv near each end thereof witha shouldered, inwardly projecting annular rib 29, suitable recesses 30 being provided in each `head. of the cylinder to accommodate said rib. The outerrface of each auxiliarypiston F and F 1s also provided with a shouldered.

annular rib 31, adapted to be engaged and actuated by the corresponding annular. rib 29 of the sleeve.

On the inner side of each main piston l) and D', near the outer end of its corresponding air cylinder 10, is provided a plurality of air ports 32 communicating with the atmos phare outside of the piston C. Each main piston D and D', on its under side, is also provided with one or more air passages see Fig. 8) which extend to the periphery of the piston proper and at certain portions of the stroke of the piston are ada ted to register with ports 34 and 35 forme in thc sleeve 22 and cylinder casting A respectively, it being understood that the assages 33 and ports 34 and 35 are similar y arranged for each power cylinder.

In each cylinder head I provide packing rings 36; all of the pistons are provided with suitable packing rings; and packing glands 37 are inserted in each of the main pistons for coperation with the auxiliary piston stems 12-12.

The operation is as follows: Assuming the parts in the position shown in Fig. 1 and with a fresh explosive mixture compressed between the auxiliary piston F and the head of the cylinder B. Upon an explosion `of said mixture, the auxiliary piston F and the main piston D are impelled downwardly or, for convenience of expression and to make the description applicable to both ends of the engine, on their out or power stroke. As the auxiliary piston F and power piston l) travel together under the impulse of the explosion, it is obvious that the air Iwhich is contained within the lower air cylinder 10 and chamber 11 wlll be compressed, duc to the, fact that the lower air piston E moves relatively inwardly of the descending lower air cylinder 10, (see Fig. 2 where the partel are shown with the piston D approximately at half stroke). Upon a continuation of the downward movement ot' the pistons F and D, the air in the chamber l1 will he still more compressed and when, near the end of the outer or power stroke, of the piston l), the sleeve 22 has been raised .so that the upper ports 26 thereof aline willi the exhaust ports 21, the pressure in the cylinder ll will e relieved and the air which is compressed within the air chamber ll will expand and :ultomatic-ally push the auxiliary piston lf upwardly until it engages with the head ol the cylinder B, which is the position shown in Fig. 3. During the linal. portion of the outer or power stroke of the piston D and during the initial portion ot' its return stroke, the intake ports 2li-25 ot' the sleeve 22 are in communicat ion with the intake ports 1.9--19 and thus a l'rcsli charge oi' liul cxplosive mixture is drawn in by the upwardly moving auxiliar \l piston l" between the main or power piston l) and thc under side of the auxiliary piston l"` see Fig. 2i. 'l`hc timing pressed the air in the cylinder more, and` of the auxiliary iston F and the power piston D is sucht at the former reaches its uppermost osition substantially atthe same time that tie latter reaches its lowermost position. As the cycle of operations continues, the auxiliary piston F is slowly lowered by being actuated by the sleeve 22 and the ower piston starts on its return or instrolle. During this relative approaching movement of the auxiliary piston F and power piston D, the new charge is colnpressed therebetween and the mixture is vforced through the by-passes 28-28 until the same is gradually displaced from the space between the auxiliary and the power piston to the compression space above the auxiliary piston, whereupon the next explosion takes place and the cycle of operations is repeated.

The foregoing described operation is based on the assumption that the engine is running. When the engine is started, and there is no explosive mixture in either of the oWer cylinders, the engine may be cranked 1n the usual manner, whereupon the following action occurs:

Assuming the parts as shown in Fig. 1 and conlining the description .to the upper cylinder, as before, as the power piston is forced downwardly by the cranking operation, the auxiliary piston F will lag somewhat and leave a space between it and the power piston. As the power piston is lowered so as to uncover the intake ports, the partial vacuum between the auxiliary piston and the power Jpiston `will cause the mixture to be drawn 1n and upon the return or iii-stroke of the power piston this new charge partly mixed with alr will be compressed, as heretofore described, and forced around and to the top side of the auxiliary piston. This weak mixture being exploded by the spark, will force the auxiliary and power pistons down and if the strength of the explosion is not suiiicient to force the auxiliary piston down to its lowermost intended stroke, a greater vacuum than before will be created between the auxiliary piston and the power piston due to the fact that the. auxiliary piston having been forced down farther will have comupon expansion of the air, the auxiliary piston will be forced farther away fuoln the head of the power piston. A greater quantit of the explosive mixture will, therefore, ble draw-n in when the intake ports are uncovered. The up-stroke of the power piston will of course compress the charge a-nd force it to the top side of the auxiliary piston in the manner heretofore described, and u on being ignited the explosion will orcet e auxiliary and power pistons down. In this way, one or two turns of:` the crank shaft will be sullicient to start the engine, as will be understood.

consequently heretofore been stated that the auxiliary the air ports 32 at a point in the It is also ap arent that in the operation of the engine, t e return inde endent stroke of the auxiliary pistons is facllitated, due to the fact that there wil be a partial vacuum onthe outer sides of the air pistons E and E,that is. between said air pistons and the heads of the ower pistons.

Although t le preceding description of th operation has been confined to the upper cylinder B, it will be understood that the same series of operations take place with regard to the lower cylinder B and that therefore the double ended piston C is given an impulse at the beginning of each of its up and down strokes. l 1 l It will also be observed that gas cushions, that is either the explosive gas or air or a mixture of both, will be formed between the auxiliary pistons and the power pistons as the two come together; between the air pistous and the heads of the air cylinders or under sides of the power pistons; between the shouldered ribs on the sleeves and the shouldered auxiliary pistons; and also between the auxiliary pistons and the main cylinder heads when the auxiliary pistons have their independent or return strokes. These fluid cushions materially contribute to the smooth running of the engine and minimize the shocks which might otherwise occur should the moving parts be permitted to strike each other at high speed. It has )l5- tons draw in the new charges and it will noted that. on account of th. strokes of the auxiliary pistons being greater than that of the power pistons, the charges so drawn in will be larger than is possible in the usual types of internal combustion engines.

Speed 'regulation of the aumliary piatfmaln the operation of the engine, when the exhaust .ports of the upper cylinder B are opened and the preure on the outer side of therauxiliary piston F is relieved and the latter is impelled upwardly due to, the expansion of the air in the chamber 11 and the partial vacuum on the outer side of the air piston E, the speed of this return or independent movement of the auxiliary piston F is regulated by the air ports 32-32 which permit whatever air is ou the outer or upper side of the nir piston E to escape. The area of these air ports Y32, being a conv stunt, will, so far as these ports 3:2 alone are concerned, result in the ret urn or independent movements ofthe auxiliary pistoni*` taking place at a uniform rate. When the engine is speeded up, it is necessary that the auxiliary piston F make its return or independent stroke faster `than when the engine is running slower and for this reason, rthe air relief passages 33, 34 and 35 have been provided which, when the engine is running faster, will augment the relief afforded by actually Cil elapsed time in the independent stroke of the auxiliary piston relatively sooner than they do when the engine is ruiming slower'. In otherI words, when the engine is running slow thc relief afforded by the air ports 3Q alone, during the independent stroke of the auxiliary piston F, extends over a longer )ortion of the actual time consumed by the independent stroke and the relief afforded by the combined air ports 3Q and relief passages 33, 34 and 35 over a shorter portion of the actual time consumed by the independent stroke, than when the engine is running faster.

From the preceding description it will be seen that the auxiliary )istons completely expel the exploded or urned gases and thus insure a pure mixture for each explosion. The arrangement is also simple and consists of a minimum number of parts, since I employ only one member, namely the sleeve, for operatin all the intake and exhaust ports, which s eeve also positively separates the auxiliary pistons from the heads of the cylinders after the burned gases have been expelled to provide compression spaces for the new charges. Another advantage inherent in my construction is the relatively large area of the intake and exhaust ports, thus insuring quick act-ion at all times and in the admission of the new charges of explosive mixture, it is apparent that the same will have a cooling effect on the main or power pistons, since the incoming mixture passes over the top of said pistons,

Another important advantage of' my improvement resides in the means automatically operating and governing the scavenging or auxiliary pistons. This air or other Huid medium is contained within the main piston itself, thus minimizing Space required, and the same body of air or other elastic fluid is used over and over to operate ,the auxiliary pistons and the compression of this contained air is automatically obtained by the power generated within the engine and outside source ot' compressed air or other medium is not necessary or required for the successful operation of these auxiliary pistons.

Another advantage resides in the fact that the stems or rods for the auxiliary pistons are never exposed to the hot exploded mixtures and consequently the same are not subject to corrosion or pitting.

Although I have herein shown and described my improvement in connection with a pair of cylinders arranged in tandem, yet the invention is by no means confined to such an engine but is equally applicable to other engines of either the single cylinder or multiple cylinder arranged' side by side, types and I do not wish to be confined to the specific structure herein shown and described,

and contemplate all changes, modifications and \ariations that come within the scope of the claims appended hereto.

I claim 1. In an internal combustion engine, the combination with a cylinder and power piston, of a scavenging piston interposed between the power piston and the head of said c linder and adapted to engage the latter to t iereby expel the burnt gases, a piston rod connected to the said scaven ing piston and passing through the head o the power piston, an air piston carried by said piston rod, an air -cylinder within which said air piston operates, said air cylinder having its axis coinciding with the axis of the main cylinder, said scavenging piston being movable with the power piston on its power stroke and independently movable thereof on its return stroke, the air in the said air cylinder being compressed on the power stroke of said power piston.

2. In an internal combustion engine, the combination with a. cylinder. a main piston coperable therewith, and au auxiliary piston in the cylinder movable with the main piston on its out strokes, of a movable member outside of said auxiliary piston and having by-passes providing communi ration bctween the spaces on opposite sides of the auxiliary piston when the latter is near its innermost position. and yielding means for causing the auxiliary piston to return on its ill-stroke and thereby completely' scavenge the cylinder.

3. In an internal combustion engine, the combination with a. cylinder provided with an exhaust'. port adjacent its head end and intake port adjacent to the limit of travel of the power piston on its ont stroke, a power piston, and an auxiliary piston in said cylinder movable with the power piston on its out` or expansion stroke., and air pressure operated means within the power piston for actuating said auxiliary piston on its return stroke and to force the same against the head of the cylinder and-thereby expel all the burnt gases.

l. In an internal combustion engine, the combination with a power cylinder, a power piston, of an auxiliary piston, said power piston having an interior air cylinder, an air piston working in said air cylinder adapted alternately to compress the air therewithin and be impelled by the expansion thereof, and a piston rod connecting said auxiliary piston. and said air piston, said air cylinder' heilig pronided with a plurality of air ports near the outer end thereof. sonic of said air ports being uncovered on the outer side of said air piston when the latter is at the limit of its stroke after the air has expanded.

5. In an internal combustion engine, the combination with a cylinder, power piston,

and auxiliary piston, the latter being mov- 9. In an internal combustion engine, the able with the power piston on the power combination with a cylinder, a sleeve slidstrokes and independently movable on its ably mounted within said cylinder, a power return strokes, said cylinder being provided piston mounted within said sleeve, an auxilwith exhaust ports near the head thereof lary piston interposed between the power and with intake ports so located and conpiston and the head end of the cylinder, the trolled as tobe o en when the power iston auxiliary pieton and power piston moving is near the end o its power Stroke, sai auxtogether on the power stroke, and means for iliary piston returning on its independent actuating the auxiliary' piston independstrokes in advance of thc power piston and entl of and inudvance of the power piston 15 thereby drawing in new charges through the on its return stroke, of ineens regulating intake ports and simultaneously expelling the speed of the return inde endent strokes burned gases through the exhaust ports, of of the auxiliary piston, sai means includa mechanically operated sleeve valve for ing relief ports carried by said sleeve. opening and closing said intake and exhaust 10. In an internal combustion engine, the ports. combination with a cylinder having exhaust i 6. In an internal combustion engine, the ports near its head end and intake ports combination with a cylinder, power piston, near its opposite end, a slidable sleeve valve and auxiliary piston between the cylinder mounted within said cylinder and having head'and the power piston, said auxiliary ports adapted to register with said intake 85. piston being movable independently of the and exhaust ports, a power piston, and an ower piston on its return stroke, of means flllXlill'y piston movable with the power or returning the auxiliary piston to the pist/0H Ori its power Strokes and independcylinder head in advance of the return cntly movable thereof on its return strokes, stroke of the power piston, and means for 0f llllld PWS-Sure means for imparting the 90 separating the auxiliary piston from the lmlpondnt l'etlllrl SU'OkBS t0 the allXlllaIy cylinder head a short distance during the piston, said sleeve being simultaneously return stroke of the power piston to promovable with but in opposite directions to Vide a con'ipression space, .said last named ill@ P OWEI' plSiO und adapted to actuaire the means including a sleeve having ports adaptauxiliary piston away from the head end of ed to register with the cylinder intake and ilu cylinder to thereby provide a compresexhaust ports. sion space, during the return stroken the 7. In an internal combustion engine, the DOWN' PISOH: combination with a cylinder, power piston, l1. ln an internal conibustlon engine, the

and auxiliary piston between the cylinderI combination with a power cylinder, a slidhead and the power piston, the auxiliary able sleeve valve mounted within said cylinpiston being movalilil independently ot the der. the` cylinder having intake and exhaust power piston on its return stroke, ot means portel and the Sleeve corresponding porte` for returning the auxiliary piston to the adapted to register therewith, a power piscylinder head in advance of the return 'full llfwlllgr un all' Cylinder, un auxiliary pis- 105 Stroke of the power piston. und incans lfor i011 lrliv'pOSEil betwefm the POWGIv piston separating the auxiliary piston from the and the head en. of the cylinder, an au' cylinder head a short distance during the piston mounted within said air cylinder and return stroke, of the, power piston t() thereconnected with theauxiliary piston, said b provide a compression space for the exauxiliary piston being movable with the p osive mixture, said last named means inpower piston on the power strokes, means cluding a sleeve valve mechanically operated for compressing thc` air within said nir cyland movable simultaneously with but 1n Opinder, thc expansion of the air within Said posite directions to the power piston.

air cylinder inipclling the auxiliary piston 8. ln au internal combustion engine, the to the head end of thc power cylinder in c dcombination with a cylinder, power piston, vence of the return stroke of the power pisand auxiliary piston, the power piston havton. and I iieclianisni for reciprocating .sai ing a shorter stroke than the auxiliary pis- Sleeve. Said sleeve engaging the auxiliary ton and the latter being adapted to engage Ill-Stor! i0 IHOVO lt away flOm the head Bild with the cylinder head, of mechanism for of thv Cylinder und thereby provide a com- 12o imparting a relatively short outward movebustine auae during the return Stroke o ment to the auxiliary piston from the cylinthe power piston. der heul prior to the power piston reachf lllri au internal combustion engine, ,the

ing its, innermost pogtlon t() thereby pronmlllmtilll Witll il POWGI' Gylllldel having ride a space for the explosive mixture bea spark plug located centrally of the head tween the auxiliary piston and the cylinder thereof, said cylinder having a plurality of4 head, said mechanism including a sleeve exhaust ports adjacent the head, and a pluslidab'le within said cylinder and having rality oi intake ports adjacent the outer ports adapted to register with the cylinder limit of travel of the ower piston, and a intake and exhaust ports. power piston, of an auxiliary pistonfa sleeve lll i arranged grooves valve slidably mounted within the cylinder and having ports 4adapted to register simultaneously with the corresponda intake and exhaust ports of the power cy inder, said sleeve valve being provided adjacent its head end with an inwardly projecting shoulder adapted to engage said auxiliary piston and draw it a short distance away from the cylinder head to thereby form a compression space, said sleeve being also provided with a plurality of longitudinally passing around said shoulder and adapted to transfer the explosive mixture around the head of said auxlliary iston.

13. n an internal combustion engine, the combination with a power cylinder having a plurality of exhaust ports adjacent the head thereof, and a plurality of intake uorts adjacent the outer limit of travel o the power piston, and a power piston, of an auxiliary piston, and a sleeve'valve, said power piston being connected with ther-,rank shaft, and having contained within itself an air cylinder which coacts with the auxiliary piston, and provided adjacent the inner end thereof with a plurality of air release holes and passages, the latter extending through the metal of the power piston to its periphery, and adapted to register with correspondui'n holes in said sleeve valve to thereby furnish additional means of exit for air from said air cylinder.

14. In an internal eombustiou engine` the, combination with a Cylinder. 4power piston and auxiliary piston. said cylinder being provided with exhaust ports near the head thereof and with intake ports so located and controlled as to be open when the power piston is near the end of its power stroke, said auxiliary piston returning on its ius'troke in advance, ot the power piston `to thereby draw in a new charge through tho intake ports and simultaneously expel burnt gases through the exhaust ports. of a sleeve valve for opening and closing said intake and exhaust ports.

l5. l'n an engine of the, eliarart'er described, the eombinal ion with a e vlinder and power piston. of a sleeve slidably mounted Within said.o \'linder between the power piston aml the walls ot the c vlinder. vsaid e \'linder being provided with intake and exhaust ports and said sleeve eontrolling `said ports, of a scavenging piston wit-hin said' rylinder, said sleeve being provided with by-passes to thereby permit lransferenre of gases from onel side. ofsaid seni-engin;lr piston to the other.

lt. In an .internal r-,ombnstion engine, the combination with a eylinder. a main pieton r'ot'iperable therewith, and an auxiliary pis-I ton in the cylinder movable with the main piston on the power strokes of the latter, of A a movable member disposed outside of said auxiliary piston having by-passes providing eon'nnunieation between the spaces on o posite sides of the .auxiliary piston when t e latter is near its innermost position, and fluid means eo-acting with said auxiliary piston to return the latter on its in-stroke in advance of the return stroke of the main piston.

17. In an internal combustion engine, the combination with a cylinder, a main piston eoperable therewith, and an auxiliary scavenging piston movingr in unison with the main piston on the power stroke of the latter, the auxiliary piston being movable independently of the main piston on its return stroke, of fiuid pressure means for inlparting said independent movements to the auxiliary piston,"and means for automatirally regulating the speed ofthe independent return strokes of the auxiliary piston, said means including a plurality of air passages in stationary and movable elements of the engine, said air passages being adapted to aline at certain predetermined points in the evcle of operation ofthe engine.

1S. In an internal combustion engine. `the combination with a cylinder, a hollow power piston and an auxiliary piston interposed between the power piston and the head end ot' the eylimler, saidlauxiliary piston hav ing a'portion thereof extending and movable within said hollow power piston, theI auxiliary and power pistons moving together on the power strokes` ot' means in axial alimL ment with the cylinder and pistons for actu ating the auxiliary piston independentl)Y of and in advance of the power piston on the return strokes. and automatically variable means for governing the speed of the independent return strokes of the auxiliary piston. said last named means includinga. member slidably mounted within the Cyl inder and havingr an air passagewayadapted to provide comuluniration between the atmosphere and the interior of the power piston to thereby allow dist-barge of air from within the ipower piston during the inde pendent movements ot the auxiliary piston and its said portion disposed within the power piston.

ln witness that l rlailn the foregoing: l have hereunto subsrribed my namel this 2nd day ol' April ltll.

ALLAN S. HUS'IED, Witnesses:

(",mmry (i. liaxz, i (iraniani: VHKERY. 

